Thank you so much for your constructive feedback!
I initially did want the player to be able to adjust before beginning the simulation. But then I also thought making it a tad frustrating might be a good thing? Haha. And also it seemed more face pace to just drag and release without the start button. But then after some time looking at feedbacks from everyone it does seem much better if players are able to adjust it first, at least to have a better feel of the game mechanics first.
Again, thanks so much for your support! It means a lot to me.